Voltage regulator with power rail tracking

ABSTRACT

Disclosed herein are related to an integrated circuit to regulate a supply voltage. In one aspect, the integrated circuit includes a metal rail including a first point, at which a first functional circuit is connected, and a second point, at which a second functional circuit is connected. In one aspect, the integrate circuit includes a voltage regulator coupled between the first point of the metal rail and the second point of the metal rail. In one aspect, the voltage regulator senses a voltage at the second point of the metal rail and adjusts a supply voltage at the first point of the metal rail, according to the sensed voltage at the second point of the metal rail.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/535,206, filed on Nov. 24, 2021, which is a continuation of U.S.patent application Ser. No. 16/775,570, filed on Jan. 29, 2020, each ofwhich is incorporated herein by reference in its entirety.

BACKGROUND

Developments in an integrated circuit design allow an integrated circuitto perform complex functionalities. In one aspect, multiple circuits canbe integrated into a single integrated circuit, where each circuit maybe designed to perform or execute a corresponding functionality. In somecases, different circuits can operate according to different powerdomains. For example, a digital circuit may operate according to a lowersupply voltage (e.g., 1.0 V), where an analog circuit or a radiofrequency (RF) circuit may operate according to a higher supply voltage(e.g., 1.5V). Different power domains may help different circuits tooperate in an efficient manner, for example, in terms of power andspeed.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a diagram of a system including a voltage regulator forregulating a supply voltage, in accordance with one embodiment.

FIG. 2 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 3 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 4 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 5 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 6 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 7 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 8 is a diagram of a voltage regulator, in accordance with oneembodiment.

FIG. 9 is a flowchart of a method of regulating a supply voltage at onepoint of a power rail according to a voltage at another point of thepower rail, in accordance with some embodiments.

FIG. 10 is a flowchart of a method of regulating a first supply voltageat a first metal rail according to a second supply voltage at a secondmetal rail, in accordance with some embodiments.

FIG. 11 is an example block diagram of a computing system, in accordancewith some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Disclosed herein are related to an integrated circuit to regulate asupply voltage. In some embodiments, the integrated circuit includes oris coupled to a metal rail including a first point, at which a firstfunctional circuit is connected and a second point, at which a secondfunctional circuit is connected. Each of the one or more functionalcircuits may include an active circuit that consumes power through themetal rail to perform a corresponding functionality. In one aspect, theintegrate circuit includes a voltage regulator coupled between the firstpoint of the metal rail and the second point of the metal rail. In oneaspect, the voltage regulator senses a voltage at the second point andadjusts the supply voltage at the first point of the metal rail,according to the sensed voltage at the second point of the metal rail.

In some embodiments, the integrated circuit includes a transistorincluding a drain electrode coupled to the first point of the metalrail, and a gate electrode coupled to the second point of the metalrail. In this configuration, the transistor may sense the voltage at thesecond point and adjust the supply voltage at the first point of themetal rail, according to the sensed voltage at the second point of themetal rail. In one aspect, the metal rail has a parasitic resistancethat may cause a voltage at the first point of the metal rail and avoltage at the second point of the metal rail to differ. According tothe integrated circuit including the transistor having the gateelectrode coupled to the second point of the metal rail, the supplyvoltage at the second point of the metal rail can be regulated.

FIG. 1 is a diagram of a system 100 including a voltage regulator 110for regulating a supply voltage, in accordance with one embodiment. Insome embodiments, the system 100 is embodied as an electronic system,device, or an integrated circuit. In some embodiments, the system 100includes a power source 105, the voltage regulator 110, and functionalcircuits 120A, 120B, 120C. In one aspect, the system 100 performsmultiple functionalities according to multiple power domains. In someembodiments, the system 100 includes more, fewer, or differentcomponents than shown in FIG. 1 . For example, the system 100 includes adifferent number of functional circuits 120 than shown in FIG. 1 .

The power source 105 is a component that provides supply voltages VDD,VSS to the voltage regulator 110. In some example, the supply voltageVDD is 1.5V and the supply voltage VSS is 0V. In some cases, the powersource 105 is implemented as battery (e.g., 1.5V). In some cases, thepower source 105 is implemented as a circuitry that receives externalpower and generates the supply voltages VDD, VSS according to theexternal power. For example, the power source 105 receives an AC inputvoltage and converts the AC input voltage into DC voltages VDD, VSS. Foranother example, the power source 105 receives a DC input voltage andconverts the DC input voltage into different DC voltages VDD, VSS.

The voltage regulator 110 is a component that receives the supplyvoltages VDD, VSS and generates different supply voltages VDDAI, VSSAIfor different power domains. For example, the voltage regulator 110 mayprovide the supply voltage VDDAI through the metal rail M11 and providethe supply voltage VSSAI through the metal rail M21. In oneconfiguration, the voltage regulator 110 is coupled to metal rails M11and M21. The voltage regulator 110 may be electrically coupled between apoint 125A of the metal rail M11, and a point 125E of the metal railM11. For example, a first output of the voltage regulator 110 is coupledto the point 125A of the metal rail M11, and a first input of thevoltage regulator 110 is coupled to the point 125E of the metal railM11. In addition, the voltage regulator 110 may be electrically coupledbetween a point 128A of the metal rail M21, and a point 128E of themetal rail M21. For example, a second output of the voltage regulator110 is coupled to the point 128A of the metal rail M21, and a secondinput of the voltage regulator 110 is coupled to the point 128E of themetal rail M21.

In one implementation, the functional circuits 120A, 120B, 120C arepowered according to supply voltages provided through the metal railsM11, M21. The functional circuits 120A, 120B, 120C may include activecircuits (e.g., transistors) that are configured to perform or executedifferent functionalities. In one example, the functional circuit 120Ais coupled between a point 125B of the metal rail M11 and a point 128Bof the metal rail M21. In one example, the functional circuit 120B iscoupled between a point 125C of the metal rail M11 and a point 128C ofthe metal rail M21. In one example, the functional circuit 120C iscoupled between a point 125D of the metal rail M11 and a point 128D ofthe metal rail M21. In one aspect, the functional circuit 120A is closerto the points 125A, 128A than the other functional circuits 120B, 120C,where the functional circuit 120C is farther away from the points 125A,128A than the other functional circuits 120A, 120B.

In some embodiments, the voltage regulator 110 adaptively adjusts supplyvoltages VDDAI, VSSAI provided through the metal rails M11, M21 to allowthe functional circuits 120A-120C to operate appropriately. In oneaspect, the functional circuits 120A, 120B, 120C may be designed tooperate according to the same supply voltages VDDAI, VSSAI. However, asegment of the metal rail M11 between the point 125B and the point 125Emay have parasitic resistances RM11, RM12, RM13 (e.g., 30˜300 Ω) due tophysical characteristic of the metal rail M11. Similarly, a segment ofthe metal rail M21 between the points 128B and the point 128E may haveparasitic resistances RM21, RM22, RM23 (e.g., 30˜300 Ω) due to physicalcharacteristic of the metal rail M21. Such parasitic resistances RM11,RM12, RM13, RM21, RM22, RM23 may degrade performance of the functionalcircuits 120A, 120B, 120C. For example, a voltage at the point 125C maybe lower than a voltage at the point 125B due to the parasiticresistance RM11, and a voltage at the point 125D may be lower than thevoltage at the point 125C due to the parasitic resistance RM12.Moreover, when the functional circuits 120A, 120B, 120C are active orenabled, voltages at the points 125B, 125C may change or vary becausethe functional circuits 120A, 120B, 120C may draw current or consumepower. In one aspect, the voltage regulator 110 may sense the voltageVDD2 at the point 125E of the metal rail M11 and adjust or regulate thevoltage VDDAI provided at the point 125A of the metal rail M11 accordingto the sensed voltage VDD2. For example, if the supply voltage VDD2 atthe point 125E of the metal rail M11 decreases, the voltage regulator110 may increase the voltage VDDAI at the point 125A of the metal railM11. Similarly, the voltage regulator 110 may sense the voltage VSS2 atthe point 128E of the metal rail M21, and adjust or regulate the voltageVSSAI provided at the point 128A of the metal rail M21 according to thesensed voltage VSS2. For example, if the supply voltage VSS2 at thepoint 128E of the metal rail M21 increases, the voltage regulator 110may decrease the voltage VSSAI at the point 128A of the metal rail M21.By adaptively adjusting the supply voltages VDDAI, VSSAI according tothe sensed voltages VDD2, VSS2, the functional circuits 120A-120C canoperate as designed. Detailed descriptions on implementations andoperations of the voltage regulator 110 are provided below with respectto FIGS. 2 through 10 .

FIG. 2 is a diagram of a portion of the system 100 including a voltageregulator 110A, in accordance with one embodiment. In some embodiments,the voltage regulator 110A is coupled to metal rails M11, M12, M13. Eachof the metal rails M11, M12, M13 may include conductive metal. Each ofthe metal rails M11, M12, M13 may be on a single layer, or may be ondifferent layers connected through via contacts. In one example, themetal rail M11 provides a supply voltage VDDAI, the metal rail M12provides a supply voltage VDDHD, and the metal rail M13 provides asupply voltage VDD. The supply voltage VDD may be higher than orsubstantially equal to the supply voltage VDDHD (e.g., 1.5V), and thesupply voltage VDDHD may be higher than the supply voltage VDDAI (e.g.,1.0V). Different supply voltages VDD, VDDHD, VDDAI can be provided todifferent functional circuits to execute different operations.

In some embodiments, the voltage regulator 110A includes transistors T1,T3 to generate or regulate supply voltages VDDHD, VDDAI. The transistorsT1, T3 may be implemented as a P-type transistor (e.g., P-type MOSFET,P-type BTJ, P-type FinFET, etc.). In one example, the transistor T1 iscoupled between the metal rails M13 and M12, and the transistor T3 iscoupled between the metal rails M12 and M11. The transistors T1, T3 maybe implemented as a P-type transistor (e.g., P-type MOSFET, P-type BTJ,P-type FinFET, etc.).

In one aspect, the transistor T1 operates as a switch that enables ordisables current through the transistor T1 between the metal rails M12,M13. In other embodiments, the voltage regulator 110A includes adifferent component or a different circuit that performs thefunctionality of the transistor T1. In one configuration, the transistorT1 includes a source electrode coupled to the metal rail M13, a drainelectrode coupled to the metal rail M12, and a gate electrode coupled toan external control device. In this configuration, the transistor T1 mayenable or disable current through the transistor T1 between the metalrails M12, M13, according to a control signal SD. For example, thecontrol signal SD having a low voltage (e.g., 0V) can enable thetransistor T1 such that current may flow through the transistor T1between the metal rails M12, M13. Similarly, the control signal SDhaving a high voltage (e.g., 1.5V) can disable the transistor T1 suchthat current may not flow through the transistor T1 between the metalrails M12, M13.

In one aspect, the transistor T3 senses a voltage VDD2 at the point 125Eof the metal rail M11 and adjusts the voltage VDDAI at the point 125A ofthe metal rail M11 according to the sensed voltage VDD2. In otherembodiments, the voltage regulator 110A includes a different componentor a different circuit that performs the functionality of the transistorT3. In one configuration, the transistor T3 includes a source electrodecoupled to the metal rail M12, a drain electrode coupled to the point125A of the metal rail M11, and a gate electrode coupled to the point125E of the metal rail M11. The drain electrode of the transistor T3 maybe directly coupled to the point 125A of the metal rail M11 though aconductive trace or conductive line. Similarly, the gate electrode ofthe transistor T3 may be directly coupled to the point 125E of the metalrail M11 though a conductive trace or conductive line. In thisconfiguration, the transistor T3 can sense the voltage VDD2, andadaptively adjust the voltage VDDAI according to the sensed voltageVDD2. For example, if the supply voltage VDD2 at the point 125E of themetal rail M11 decreases, the transistor T3 may increase the voltageVDDAI at the point 125A of the metal rail M11 by increasing a currentsupplied to the point 125A. For example, if the supply voltage VDD2 atthe point 125E of the metal rail M11 increases, the transistor T3 maydecrease the voltage VDDAI at the point 125A of the metal rail M11 bydecreasing a current supplied to the point 125A. Accordingly, thetransistor T3 may regulate or control voltages at the points 125A, 125B,125C, 125D, 125E of the metal rail M11 through a negative feedback loop.Hence, the voltage regulator 110A may reduce variations or changes inthe voltages at the points 125A, 125B, 125C, 125D, 125E of the metalrail M11 to ensure stable operations of the functional circuits 120A,120B, 120C.

FIG. 3 is a diagram of a portion of the system 100 including a voltageregulator 110B, in accordance with one embodiment. The configuration ofthe voltage regulator 110B is substantially similar to the circuit 110Aof FIG. 2 , except the transistor T4 is implemented to replace thetransistor T3 of FIG. 2 . In some embodiments, the transistor T4 is aN-type transistor (e.g., N-type MOSFET, N-type BJT, N-type FinFET,etc.). The transistor T4 includes a drain electrode coupled to the metalrail M12, a source electrode coupled to the point 125A of the metal railM11, and a gate electrode coupled to the metal rail M13. The sourceelectrode of the transistor T4 may be directly coupled to the point 125Aof the metal rail M11 though a conductive trace or conductive line.Similarly, the gate electrode of the transistor T4 may be directlycoupled to the metal rail M13 (or a source electrode of the transistorT1) though a conductive trace or conductive line. In other embodiments,the voltage regulator 110B includes a different component or a differentcircuit that performs the functionality of the transistor T4.

In one aspect, a connection between the metal rail M12 and thetransistor T4 may have a parasitic resistance R1 (e.g., 30˜300 Ω). Suchparasitic resistance R1 may cause a voltage VDD3 at the drain electrodeof the transistor T4 to change or vary, which may also affect the supplyvoltages VDDAI, VDD2 at the metal rail M11. When the functional circuits120A, 120B, 120C become active, the supply voltage VDDAI may drop ordecrease due to the increased current demand from the functionalcircuits 120A, 120B, 120C. The transistor T4 can sense a change in avoltage difference between the gate electrode and the source electrode,and adjust or change a drive strength (e.g., transconductance) accordingto the sensed change in the voltage difference. For example, in responseto the decreasing voltage VDDAI, the transistor T4 may increase thedrive strength and increase current supplied through the transistor T4such that the voltage VDDAI may increase. For example, in response tothe increasing voltage VDDAI, the transistor T4 may decrease the drivestrength and reduce current supplied through the transistor T4 such thatthe voltage VDDAI may decrease. Accordingly, the bypass connection atthe gate electrode of the transistor T4 allows the transistor T4 toregulate or control a voltage VDD3 at the drain electrode and/or thevoltage VDDAI at the point 125A of the metal rail M11. Hence, thevoltage regulator 110B may reduce variations or changes in the voltagesat the points 125A, 125B, 125C, 125D, 125E of the metal rail M11 toensure stable operations of the functional circuits 120A, 120B, 120C,according to the voltage VDD at the metal rail M13.

FIG. 4 is a diagram of a portion of the system 100 including a voltageregulator 110C, in accordance with one embodiment. The configuration ofthe voltage regulator 110C is substantially similar to the voltageregulator 110B of FIG. 3 , except the transistor T5 is implemented toreplace the transistor T4 of FIG. 3 . In some embodiments, thetransistor T5 is a N-type transistor (e.g., N-type MOSFET, N-type BJT,N-type FinFET, etc.). The transistor T5 includes a drain electrodecoupled to the metal rail M12, a source electrode coupled to the point125A of the metal rail M11, and a gate electrode coupled to the metalrail M12. The source electrode of the transistor T5 may be directlycoupled to the point 125A of the metal rail M11 though a conductivetrace or conductive line. Similarly, the gate electrode of thetransistor T5 may be directly coupled to the metal rail M12 (or a drainelectrode of the transistor T1) though a conductive trace or conductiveline. In this configuration, the transistor T5 can sense a change in avoltage difference between the gate electrode and the source electrode,and adjust or change a drive strength (e.g., transconductance) accordingto the sensed change in the voltage difference. Hence, the voltageregulator 110C may reduce variations or changes in the voltages at thepoints 125A, 125B, 125C, 125D, 125E of the metal rail M11 to ensurestable operations of the functional circuits 120A, 120B, 120C, accordingto the voltage VDDHD at the metal rail M12 instead of the voltage VDD atthe metal rail M13. In other embodiments, the voltage regulator 110Cincludes a different component or a different circuit that performs thefunctionality of the transistor T5.

FIG. 5 is a diagram of a portion of the system 100 including a voltageregulator 110D, in accordance with one embodiment. In one aspect, thevoltage regulator 110D is a combination of the voltage regulator 110A ofFIG. 2 and the voltage regulator 110B of FIG. 3 . In one configuration,the voltage regulator 110D includes the transistor T3 and the transistorT4 that are coupled to each other in parallel between the metal railsM11, M12. In one aspect, the drain electrode of the transistor T3 isdirectly connected to the source electrode of the transistor T4, and thesource electrode of the transistor T3 is directly connected to the drainelectrode of the transistor T4. As described above with respect to FIG.2 , the transistor T3 can adjust or regulate the voltages at the points125A-125E of the metal rail M11, according to the voltage VDD2 at thepoint 125E of the metal rail M11. Similarly, as described above withrespect to FIG. 3 , the transistor T4 can adjust or regulate thevoltages at the points 125A-125E of the metal rail M11 according to thevoltage VDD of the metal rail M13. Hence, the voltage regulator 110D mayreduce variations or changes in the voltages at the points 125A-125E ofthe metal rail M11 to ensure stable operations of the functionalcircuits 120A, 120B, 120C.

FIG. 6 is a diagram of a portion of the system 100 including a voltageregulator 110E, in accordance with one embodiment. In one aspect, thevoltage regulator 110E is a combination of the voltage regulator 110A ofFIG. 2 and the voltage regulator 110C of FIG. 4 . In one configuration,the voltage regulator 110E includes the transistor T3 and the transistorT5 that are coupled to each other in parallel between the metal railsM11, M12. In one aspect, the drain electrode of the transistor T3 isdirectly connected to the source electrode of the transistor T5, and thesource electrode of the transistor T3 is directly connected to the drainelectrode of the transistor T5. As described above with respect to FIG.2 , the transistor T3 can adjust or regulate the voltages at the points125A-125E of the metal rail M11, according to the voltage VDD2 at thepoint 125E of the metal rail M11. Similarly, as described above withrespect to FIG. 4 , the transistor T5 can adjust or regulate thevoltages at the points 125A-125E of the metal rail M11, according to thevoltage VDDHD of the metal rail M12. Hence, the voltage regulator 110Emay reduce variations or changes in the voltages at the points 125A-125Eof the metal rail M11 to ensure stable operations of the functionalcircuits 120A, 120B, 120C.

Although voltage regulators for regulating supply voltages VDD, VDDHD,VDDAI, VDD2 are described above with respect to FIGS. 2 through 6 , theprinciples disclosed herein can be applied to regulate differentvoltages (e.g., VSS, VSSHD, VSSAI, VSS2). For example, some P-typetransistors in the voltage regulators 110A-110E in FIGS. 2-6 can bereplaced by N-type transistors, and some N-type transistors in thevoltage regulators 110A-110E in FIGS. 2-6 can be replaced by P-typetransistors.

FIG. 7 is a diagram of a portion of the system 100 including a voltageregulator 110F, in accordance with one embodiment. The voltage regulator110F may be a counter part of the voltage regulator 110D of FIG. 5 ,such that the voltage regulator 110F can generate, provide, or regulatethe supply voltages (e.g., VSS, VSSHD, VSSAI, VSS2). In someembodiments, the system 100 includes metal rails M21, M22, M23. Each ofthe metal rails M21, M22, M23 may include conductive metal. Each of themetal rails M21, M22, M23 may be on a single layer, or may be ondifferent layers connected through via contacts. In one example, themetal rail M21 provides a supply voltage VSSAI or VSS2, the metal railM22 provides a supply voltage VSSHD, and the metal rail M23 provides asupply voltage VSS. The supply voltage VSS (e.g., 0V) may be lower thanor equal to the supply voltage VSSHD, and the supply voltage VSSHD maybe lower than the supply voltage VSS2 (e.g., 0.4V). Different supplyvoltages VSS, VSSHD, VSS2 can be provided to different functionalcircuits to execute different operations.

In one implementation, the voltage regulator 110F includes transistorsT6, T7, T8 to generate or regulate supply voltages VSSHD, VSSAI. In oneexample, the transistor T6 is coupled between the metal rails M23 andM22, and the transistors T7 and T8 are coupled between the metal railsM22 and M21. The transistors T6, T7 may be implemented as a N-typetransistor, and the transistor T8 may be implemented as a P-typetransistor. In one configuration, the transistor T6 includes a sourceelectrode coupled to the metal rail M23, a drain electrode coupled tothe metal rail M22, and a gate electrode coupled to an external controldevice. In this configuration, the transistor T6 may operate as a switchthat enables or disables current through the transistor T6 between themetal rails M22, M23, according to a control signal SDB. The controlsignal SDB may be inverse of the control signal SD. For example, thecontrol signal SDB having a high voltage (e.g., 1.5V) can enable thetransistor T6 such that current may flow through the transistor T6between the metal rails M22, M23. Similarly, the control signal SDBhaving a low voltage (e.g., 0V) can disable the transistor T6 such thatcurrent may not flow through the transistor T6 between the metal railsM22, M23.

In one configuration, the transistor T7 includes a source electrodecoupled to the metal rail M22, a drain electrode coupled to a point 128Aof the metal rail M21, and a gate electrode coupled to a point 128E ofthe metal rail M21. In one configuration, the transistor T8 includes adrain electrode coupled to the metal rail M22, a source electrodecoupled to a point 128A of the metal rail M21, and a gate electrodecoupled to the metal rail M23. The source electrode of the transistor T8may be directly coupled to the point 128A of the metal rail M21 and thedrain electrode of the transistor T7 though a conductive trace orconductive line. The drain electrode of the transistor T8 may bedirectly coupled to the source electrode of the transistor T7 though aconductive trace or conductive line. Moreover, the gate electrode of thetransistor T8 may be directly coupled to the metal rail M23 (or a sourceelectrode of the transistor T6) though a conductive trace or conductiveline. In this configuration, the supply voltages VSS3, VSSAI, VSS2 canbe regulated, despite of parasitic resistances RM21, RM22, RM23, R2. Asdescribed above with respect to FIG. 5 , the transistor T7 can adjust orregulate the voltages at the points 128A-128E of the metal rail M21according to the voltage VSS2 of the metal rail M21. Similarly, asdescribed above with respect to FIG. 5 , the transistor T8 can adjust orregulate the voltages at the points 128A-128E of the metal rail M21according to the voltage VSS of the metal rail M23. Hence, the voltageregulator 110F may reduce variations or changes in the voltages at thepoints 128A-128E of the metal rail M21 to ensure stable operations ofthe functional circuits 120A, 120B, 120C. In other embodiments, thevoltage regulator 110F includes a different component or a differentcircuit that performs the functionality of the transistors T7, T8.

FIG. 8 is a diagram of a portion of the system 100 including a voltageregulator 110G, in accordance with one embodiment. The configuration ofthe voltage regulator 110G is substantially similar to the voltageregulator 110F of FIG. 7 , except the transistor T9 is implemented toreplace the transistor T8 of FIG. 7 . In some embodiments, thetransistor T9 is a P-type transistor. In one configuration, thetransistor T9 includes a drain electrode coupled to the metal rail M22,a source electrode coupled to the point 128A of the metal rail M21, anda gate electrode coupled to the metal rail M22. The source electrode ofthe transistor T9 may be directly coupled to the point 128A of the metalrail M21 and the drain electrode of the transistor T7 though aconductive trace or conductive line. The drain electrode of thetransistor T9 may be directly coupled to the source electrode of thetransistor T7 though a conductive trace or conductive line. Moreover,the gate electrode of the transistor T9 may be directly coupled to themetal rail M22 (or a drain electrode of the transistor T6) though aconductive trace or conductive line. In this configuration, the supplyvoltages VSS3, VSSAI, VSS2 can be regulated, despite of parasiticresistances RM21, RM22, RM23, R2. For example, the transistor T9 canadjust or regulate the voltages at the points 128A-128E of the metalrail M21 according to the voltage VSSHD of the metal rail M22 instead ofthe voltage VSS of the metal rail M23. Hence, the voltage regulator 110Gmay reduce variations or changes in the voltages at the points 128A-128Eof the metal rail M21 to ensure stable operations of the functionalcircuits 120A, 120B, 120C. In other embodiments, the voltage regulator110G includes a different component or a different circuit that performsthe functionality of the transistor T9.

FIG. 9 is a flowchart of a method 900 of regulating a supply voltage atone point of a power rail according to a voltage at another point of thepower rail, in accordance with some embodiments. The method 900 may beperformed by any of the voltage regulators 110A and 110D through 110G.In some embodiments, the method 900 is performed by other entities. Insome embodiments, the method 900 includes more, fewer, or differentoperations than shown in FIG. 9 .

In an operation 910, a voltage regulator (e.g., 110A and 110D-110G)provides a supply voltage (e.g., VDDAI, VSSAI) at a first point (e.g.,125B, 128B) of a metal rail (e.g., M11, M21). In one configuration, oneor more functional circuits are coupled between the first point (e.g.,125B, 128B) and a second point (e.g., 125D, 128D) of the metal rail(e.g., M11, M21). A first functional circuit 120A may be connected tothe first point (e.g., 125B, 128B) of the metal rail, and a secondfunctional circuit 120C may be connected to the second point (e.g.,125D, 128D) of the metal rail. When one or more functional circuits(e.g., 120A-120C) are active, voltages at different points of the metalrail between the first point and the second point may change or vary,for example, due to parasitic resistances of the metal rail.

In an operation 920, the voltage regulator (e.g., 110A and 110D-110G)senses a voltage (e.g., VDD2, VSS2) at the second point (e.g., 125D,128D) of the metal rail (e.g., M11, M21). In an operation 930, thevoltage regulator (e.g., 110A and 110D-110G) changes, controls,modifies, or regulates the voltage (e.g., VDDAI, VSSAI) at the firstpoint (e.g., 125B, 128B) of the metal rail (e.g., M11, M21) according tothe sensed voltage (e.g., VDD2, VSS2) at the second point (e.g., 125D,128D) of the metal rail (e.g., M11, M21). In one example, the voltageregulator (e.g., 110A and 110D-110G) includes a transistor (e.g., T3,T7) having a drain electrode coupled to the first point (e.g., 125B,128B) of the metal rail (e.g., M11, M21) and a gate electrode coupled tothe second point (e.g., 125D, 128D) of the metal rail (e.g., M11, M21).For example, if the voltage (e.g., VDD2, VSS2) at the second point(e.g., 125D, 128D) of the metal rail (e.g., M11, M21) decreases, thetransistor (e.g., T3, T7) may increase the voltage (e.g., VDDAI, VSSAI)at the first point (e.g., 125B, 128B) of the metal rail (e.g., M11,M21). For example, if the voltage (e.g., VDD2, VSS2) at the second point(e.g., 125D, 128D) of the metal rail (e.g., M11, M21) increases, thetransistor (e.g., T3, T7) may decrease the voltage (e.g., VDDAI, VSSAI)at the first point (e.g., 125B, 128B) of the metal rail (e.g., M11,M21). Through negative feedback, the voltage regulator (e.g., 110A and110D-110G) can reduce variations or changes in the voltage at the metalrail to ensure stable operations of one or more functional circuitscoupled to the metal rail.

FIG. 10 is a flowchart of a method 1000 of regulating a first supplyvoltage (e.g., VDDAI, VSSAI) at a first metal rail (e.g., M11, M21)according to a second supply voltage (e.g., VDD, VDDHD, VSS, VSSHD) at asecond metal rail (e.g., M12, M13, M22, M23), in accordance with someembodiments. The method 1000 may be performed by any of the voltageregulators 110B through 110G. In some embodiments, the method 1000 isperformed by other entities. In some embodiments, the method 1000includes more, fewer, or different operations than shown in FIG. 10 .

In an operation 1010, the voltage regulator (e.g., 110B-110G) detects,by a transistor (e.g., T4, T5, T8, T9), a change in a first voltage(e.g., VDDAI, VSSAI) at a first metal rail (e.g., M11, M21). The firstmetal rail (e.g., M11, M21) may be coupled to one or more functionalcircuits (e.g., 120A-120C). The transistor (e.g., T4, T5, T8, T9) mayinclude a source electrode coupled to the first metal rail (e.g., M11,M21), a gate electrode coupled to a second metal rail (e.g., M12, M13,M22, M23) having a second voltage (e.g., VDD, VDDHD, VSS, VSSHD), and adrain electrode directly or indirectly coupled to the second metal rail(e.g., M12, M13, M22, M23).

In an operation 1020, the voltage regulator (e.g., 110B-110G) adjusts adrive strength (or a transconductance) of the transistor (e.g., T4, T5,T8, T9), according to a change in a difference between the first voltage(e.g., VDDAI, VSSAI) at the first metal rail (e.g., M11, M21) and thesecond voltage (e.g., VDD, VDDHD, VSS, VSSHD) at the second metal rail(e.g., M12, M13, M22, M23). In an operation 1030, the voltage regulator(e.g., 110B-110G) adjusts the first voltage (e.g., VDDAI, VSSAI) at thefirst metal rail (e.g., M11, M21) according to the adjusted drivestrength of the transistor (e.g., T4, T5, T8, T9). For example, inresponse to the first voltage (e.g., VDDAI, VSSAI) at the first metalrail (e.g., M11, M21) decreasing, a difference between the secondvoltage (e.g., VDD, VDDHD, VSS, VSSHD) at the second metal rail (e.g.,M12, M13, M22, M23) and the first voltage (e.g., VDDAI, VSSAI) at thefirst metal rail (e.g., M11, M21) may increase. In response to thedifference between the second voltage (e.g., VDD, VDDHD, VSS, VSSHD) atthe second metal rail (e.g., M12, M13, M22, M23) and the first voltage(e.g., VDDAI, VSSAI) at the first metal rail (e.g., M11, M21)increasing, the transistor (e.g., T4, T5, T8, T9) may increase its drivestrength (or a transconductance) and allow more current to flow throughthe transistor (e.g., T4, T5, T8, T9) such that the first voltage (e.g.,VDDAI, VSSAI) at the first metal rail (e.g., M11, M21) can increase. Forexample, in response to the first voltage (e.g., VDDAI, VSSAI) at thefirst metal rail (e.g., M11, M21) increasing, a difference between thesecond voltage (e.g., VDD, VDDHD, VSS, VSSHD) at the second metal rail(e.g., M12, M13, M22, M23) and the first voltage (e.g., VDDAI, VSSAI) atthe first metal rail (e.g., M11, M21) may decrease. In response to thedifference between the second voltage (e.g., VDD, VDDHD, VSS, VSSHD) atthe second metal rail (e.g., M12, M13, M22, M23) and the first voltage(e.g., VDDAI, VSSAI) at the first metal rail (e.g., M11, M21)decreasing, the transistor (e.g., T4, T5, T8, T9) may decrease its drivestrength and allow less current to flow through the transistor (e.g.,T4, T5, T8, T9) such that the first voltage (e.g., VDDAI, VSSAI) at thefirst metal rail (e.g., M11, M21) can decrease. In one aspect, accordingto a bypass connection at the gate electrode of the transistor (e.g.,T4, T5, T8, T9) coupled to the second metal rail (e.g., M12, M13, M22,M23), the voltage regulator (e.g., 110B-110G) can reduce variations orchanges in the voltage (e.g., VDDAI, VSSAI) at the first metal rail(e.g., M11, M21) to ensure stable operations of one or more functionalcircuits (e.g., 120A-120C) coupled to the first metal rail (e.g., M11,M21).

Referring now to FIG. 11 , an example block diagram of a computingsystem 1100 is shown, in accordance with some embodiments of thedisclosure. The computing system 1100 may be used by a circuit or layoutdesigner for integrated circuit design. A “circuit” as used herein is aninterconnection of electrical components such as resistors, transistors,switches, batteries, inductors, or other types of semiconductor devicesconfigured for implementing a desired functionality. The computingsystem 1100 includes a host device 1105 associated with a memory device1110. The host device 1105 may be configured to receive input from oneor more input devices 1115 and provide output to one or more outputdevices 1120. The host device 1105 may be configured to communicate withthe memory device 1110, the input devices 1115, and the output devices1120 via appropriate interfaces 1125A, 1125B, and 1125C, respectively.The computing system 1100 may be implemented in a variety of computingdevices such as computers (e.g., desktop, laptop, servers, data centers,etc.), tablets, personal digital assistants, mobile devices, otherhandheld or portable devices, or any other computing unit suitable forperforming schematic design and/or layout design using the host device1105.

The input devices 1115 may include any of a variety of inputtechnologies such as a keyboard, stylus, touch screen, mouse, trackball, keypad, microphone, voice recognition, motion recognition, remotecontrollers, input ports, one or more buttons, dials, joysticks, and anyother input peripheral that is associated with the host device 1105 andthat allows an external source, such as a user (e.g., a circuit orlayout designer), to enter information (e.g., data) into the host deviceand send instructions to the host device. Similarly, the output devices1120 may include a variety of output technologies such as externalmemories, printers, speakers, displays, microphones, light emittingdiodes, headphones, video devices, and any other output peripherals thatare configured to receive information (e.g., data) from the host device1105. The “data” that is either input into the host device 1105 and/oroutput from the host device may include any of a variety of textualdata, circuit data, signal data, semiconductor device data, graphicaldata, combinations thereof, or other types of analog and/or digital datathat is suitable for processing using the computing system 1100.

The host device 1105 includes or is associated with one or moreprocessing units/processors, such as Central Processing Unit (“CPU”)cores 1130A-1130N. The CPU cores 1130A-1130N may be implemented as anApplication Specific Integrated Circuit (“ASIC”), Field ProgrammableGate Array (“FPGA”), or any other type of processing unit. Each of theCPU cores 1130A-1130N may be configured to execute instructions forrunning one or more applications of the host device 1105. In someembodiments, the instructions and data to run the one or moreapplications may be stored within the memory device 1110. The hostdevice 1105 may also be configured to store the results of running theone or more applications within the memory device 1110. Thus, the hostdevice 1105 may be configured to request the memory device 1110 toperform a variety of operations. For example, the host device 1105 mayrequest the memory device 1110 to read data, write data, update ordelete data, and/or perform management or other operations. One suchapplication that the host device 1105 may be configured to run may be astandard cell application 1135. The standard cell application 1135 maybe part of a computer aided design or electronic design automationsoftware suite that may be used by a user of the host device 1105 touse, create, or modify a standard cell of a circuit. In someembodiments, the instructions to execute or run the standard cellapplication 1135 may be stored within the memory device 1110. Thestandard cell application 1135 may be executed by one or more of the CPUcores 1130A-1130N using the instructions associated with the standardcell application from the memory device 1110. In one example, thestandard cell application 1135 allows a user to utilize pre-generatedschematic and/or layout designs of a system 100 or a portion of thesystem 100. After the layout design of the integrated circuit iscomplete, multiples of the integrated circuit, for example, includingthe system 100 or a portion of the system 100 can be fabricatedaccording to the layout design by a fabrication facility.

Referring still to FIG. 11 , the memory device 1110 includes a memorycontroller 1140 that is configured to read data from or write data to amemory array 1145. The memory array 1145 may include a variety ofvolatile and/or non-volatile memories. For example, in some embodiments,the memory array 1145 may include NAND flash memory cores. In otherembodiments, the memory array 1145 may include NOR flash memory cores,Static Random Access Memory (SRAM) cores, Dynamic Random Access Memory(DRAM) cores, Magnetoresistive Random Access Memory (MRAM) cores, PhaseChange Memory (PCM) cores, Resistive Random Access Memory (ReRAM) cores,3D XPoint memory cores, ferroelectric random-access memory (FeRAM)cores, and other types of memory cores that are suitable for use withinthe memory array. The memories within the memory array 1145 may beindividually and independently controlled by the memory controller 1140.In other words, the memory controller 1140 may be configured tocommunicate with each memory within the memory array 1145 individuallyand independently. By communicating with the memory array 1145, thememory controller 1140 may be configured to read data from or write datato the memory array in response to instructions received from the hostdevice 1105. Although shown as being part of the memory device 1110, insome embodiments, the memory controller 1140 may be part of the hostdevice 1105 or part of another component of the computing system 1100and associated with the memory device. The memory controller 1140 may beimplemented as a logic circuit in either software, hardware, firmware,or combination thereof to perform the functions described herein. Forexample, in some embodiments, the memory controller 1140 may beconfigured to retrieve the instructions associated with the standardcell application 1135 stored in the memory array 1145 of the memorydevice 1110 upon receiving a request from the host device 1105.

It is to be understood that only some components of the computing system1100 are shown and described in FIG. 11 . However, the computing system1100 may include other components such as various batteries and powersources, networking interfaces, routers, switches, external memorysystems, controllers, etc. Generally speaking, the computing system 1100may include any of a variety of hardware, software, and/or firmwarecomponents that are needed or considered desirable in performing thefunctions described herein. Similarly, the host device 1105, the inputdevices 1115, the output devices 1120, and the memory device 1110including the memory controller 1140 and the memory array 1145 mayinclude other hardware, software, and/or firmware components that areconsidered necessary or desirable in performing the functions describedherein.

One aspect of this description relates to an integrated circuit. In someembodiments the integrated circuit includes a metal rail including afirst point, at which a first functional circuit is connected, and asecond point, at which a second functional circuit is connected. In someembodiments, the integrate circuit includes a voltage regulator coupledto the first point of the metal rail and the second point of the metalrail. In some embodiments, the voltage regulator senses a voltage at thesecond point of the metal rail, and adjusts a supply voltage at thefirst point of the metal rail, according to the sensed voltage at thesecond point of the metal rail.

One aspect of this description relates to an integrated circuit. In someembodiments, the integrated circuit includes a first transistor coupledbetween a first metal rail and a second metal rail and a secondtransistor coupled between the second metal rail and a third metal rail.In some embodiments, the third metal rail is coupled to one or morefunctional circuits. In some embodiments, the second transistor senses achange in a difference between a first voltage at a source electrode ofthe second transistor coupled to the third metal rail and a secondvoltage at a gate electrode of the second transistor coupled to thefirst metal rail or the second metal rail, due to the one or morefunctional circuits. In some embodiments, the second transistor adjustsa third voltage at a drain electrode of the second transistor accordingto the sensed change in the difference.

One aspect of this description relates to a method of regulating asupply voltage at a metal rail. In some embodiments, the method includesproviding, through a drain electrode of a transistor coupled to a firstpoint of the metal rail, a supply voltage. In some embodiments, themethod includes sensing, through a gate electrode of the transistor avoltage at a second point of the metal rail. The drain electrode of thetransistor may be coupled to the first point of the metal rail and afirst functional circuit. In addition, the gate electrode of thetransistor may be coupled to the second point of the metal rail and asecond functional circuit. In some embodiments, the method includesadjusting the supply voltage at the first point of the metal rail,according to the sensed voltage at the second point of the metal rail.The first functional circuit may be powered by the supply voltage at thefirst point of the metal rail, and the second functional circuit may bepowered by the voltage at the second point of the metal rail

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit comprising: a single metalrail configured to provide a plurality of functional circuits with asupply voltage, wherein the single metal layer has a first point and asecond point, with the plurality of functional circuits disposed betweenthe first and second points, and wherein one or more parasiticresistances are present between the first point and the second point; avoltage regulator coupled between the first point and the second pointof the single metal layer; and wherein the voltage regulator isconfigured to adjust the supply voltage according to a voltage sensed atthe second point.
 2. The integrated circuit of claim 1, wherein at leastone of the plurality of functional circuits includes an active circuit.3. The integrated circuit of claim 1, wherein the voltage regulatorincludes a first transistor including: a drain electrode coupled to thefirst point of the single metal rail; and a gate electrode coupled tothe second point of the single metal rail.
 4. The integrated circuit ofclaim 3, wherein the first transistor is configured to: sense thevoltage at the second point through the gate electrode; and adjust thesupply voltage at the first point of the single metal rail through thedrain electrode, according to the voltage sensed at the second point. 5.The integrated circuit of claim 4, wherein the voltage regulator furtherincludes: a second transistor including a drain electrode coupled to asource electrode of the first transistor, the second transistor toenable or disable current through the first transistor according to acontrol signal.
 6. The integrated circuit of claim 5, wherein the secondtransistor includes a source electrode coupled to another metal railproviding another voltage at the another metal rail higher than thesupply voltage. 7 The integrated circuit of claim 6, wherein the firsttransistor is a P-type transistor.
 8. The integrated circuit of claim 5,wherein the second transistor includes a source electrode coupled toanother metal rail providing another voltage at the another metal raillower than the supply voltage.
 9. The integrated circuit of claim 8,wherein the first transistor is a N-type transistor.
 10. The integratedcircuit of claim 5, wherein the voltage regulator further includes athird transistor coupled to the first transistor in parallel, the firsttransistor of a first type, and the second transistor of a second type.11. The integrated circuit of claim 10, wherein the third transistorincludes: a source electrode coupled to the drain electrode of the firsttransistor, and a drain electrode coupled to the source electrode of thefirst transistor.
 12. The integrated circuit of claim 11, wherein thethird transistor includes a gate electrode coupled to a source electrodeof the second transistor.
 13. The integrated circuit of claim 11,wherein the third transistor includes a gate electrode coupled to thedrain electrode of the second transistor.
 14. An integrated circuitcomprising: a switch coupled between a first metal rail and a secondmetal rail, a first supply voltage present on the first metal rail and asecond supply voltage present on the second metal rail; and a firsttransistor coupled between the second metal rail and a third metal rail,a third voltage present on the third metal rail, the third metal railcoupled to one or more functional circuits; wherein the first transistoris configured to regulate the third supply voltage based on based on avoltage difference between i) the first supply voltage or the secondsupply voltage, and ii) the third supply voltage.
 15. The integratedcircuit of claim 14, wherein the first transistor includes: a gateelectrode coupled to the first metal rail or the second metal rail; asource electrode coupled to the third metal rail; and a drain electrodecoupled to the second metal rail.
 16. The integrated circuit of claim14, further comprising a second transistor coupled in parallel with thefirst transistor between the second metal rail and the third metal rail.17. The integrated circuit of claim 16, wherein the first transistor isa first type of transistor, and the second transistor is a second typeof transistor.
 18. The integrated circuit of claim 16, wherein the oneor more functional circuits are coupled between a first point of thethird metal rail and a second point of the third metal rail, and whereinthe second transistor includes: a gate electrode coupled to the secondpoint of the third metal rail; a drain electrode coupled to the firstpoint of the third metal rail; and a source electrode coupled to thesecond metal rail.
 19. A method comprising: detecting a change in afirst supply voltage supplied along a first metal rail; adjusting atransconductance of a transistor based on a voltage difference betweenthe first supply voltage at the first metal rail and a second supplyvoltage at a second metal rail; and regulating the first supply voltageaccording to the adjusted transconductance.
 20. The method of claim 19,further comprising: receiving, at a drain electrode of the transistorcoupled to the second metal rail, the second supply voltage; andproviding, at a source electrode of the transistor coupled to the firstmetal rail, the first supply voltage.